We are investigating the extent and mechanisms underlying synaptic interactions in the vertebrate retina. By impaling individual neurons with fine microelectrodes we are hoping to understand the nature and specificity of the synaptic pathways by which one class of neuron "drives" or influences the response in another class. Of considerable interest are the specific mechanisms underlying the communicaton between cells. What is the synaptic transmitter, what is the duration of the elementary event transmitter-activated conductance event on the postsynaptic cell? What is the size of the event? We have been and will continue to perfect the techniques of noise analysis to answer the above questions. In addition we are using pharmacological and morphological techniques to buttress and compliment these studies.